1. Field of the Invention
The present invention relates to an electrical connection box such as a junction box used for an automotive vehicle and is designed to make the electrical connection box smaller and lighter and to reduce the number of parts by making internal circuits accommodated in the electrical connection box highly functional.
2. Description of the Related Art
Internal circuits of a prior art electrical connection box, such as a junction box, typically are formed by busbars. A prior art busbar is formed by punching a conductive metal sheet and, in many cases, a plurality of such busbars are placed one over another with insulating plates held therebetween.
Busbars need to be newly worked in the case of a circuit change, and this reworking leads to an increase in production costs. Circuit change is necessitated relatively frequently on internal circuits of load side circuits downstream from a fuse. Consequently these internal circuits often are formed by wires (single-core wires) and cramping terminals to be pressingly connected with the wires. Further, a printed circuit board having electronic devices such as relays, diodes and capacitors mounted thereon may be provided in the prior art electrical connection box.
A known highly functional electrical connection box is shown in FIG. 5, and has upper and lower casings 1 and 2. Busbars 3 and insulating plates 4 are laminated in a laminated portion 5. The laminated portion 5 and a printed circuit board 6 are accommodated in different levels in a casing comprised of the upper casing 1 and the lower casing 2. The busbars 3 and the printed circuit board 6 are connected via connectors 7 which are intermediate parts. Each connector 7 has a connector housing 7a mounted on an outer edge of the printed circuit board 6. Male terminals 3a in the form of tabs are formed by bending the busbars 3. The male terminals 3a are inserted into the respective terminal chambers of the connector housing 7a, and are connected with female terminals 7b set in the connector housing 7a. The female terminals 7b and a conductive portion of the printed circuit board 6 are connected as follows. Ends of a circuit portion arranged on the rear surface of the insulating board 6a of the printed circuit board 6 are extended to the outer edges of the printed circuit board 6. A copper leaf or area is exposed only at leading ends 8 of the circuit portion which are aligned. An electrical connection then is established by holding the leading ends 8 of the circuit portion by the female terminals 7b.
In an electrical connection box shown in FIG. 6 and FIG. 7, a busbar 3, a printed circuit board 6 and an internal circuit formed by single-core wires 9 and cramping terminals 10 are accommodated at different levels in a casing comprised of an upper casing 1 and a lower casing 2. In this electrical connection box, hollow box-shaped female intermediate terminals 11 are provided on the printed circuit board 6. A pair of leg portions 11a project from the bottom ends of the intermediate terminals 11 and are inserted through holes 6b formed in the insulating board 6a of the printed circuit board 6. The leg portions 11a are mounted at the lower surface side of the insulating plate 6a and are connected with a conductive portion via solder 12 as shown in FIGS. 7(A) and 7(B). Tab-shaped male terminals 3a of the busbars 3 and tab-shaped male terminals 10a of the cramping terminals 10 that connect with the single-core wires 9 are inserted into the intermediate terminals 11 for electrical connection.
In the electrical connection box shown in FIG. 5, the busbar terminals 3a and the conductive portion of the printed circuit board 6 are connected via the connectors 7 as the intermediate parts. Hence the number of parts and the number of assembling steps are increased, thereby increasing costs for parts, assembling and maintenance and accordingly production costs. Likewise, the cramping terminals 10 connected with the single-core wires 9 and the busbar terminals 3a are connected with the conductive portion of the printed circuit board 6 via the intermediate terminals 11 in the electrical connection box shown in FIGS. 6 and 7. Thus the number of parts and the number of assembling steps are increased, thereby increasing costs for parts, assembling and maintenance and accordingly production costs.
Further, the use of the connectors 7 and the intermediate terminals 11 as the intermediate parts necessitates a space for providing them and makes the electrical connection box larger and heavier. Therefore, it is difficult to make the electrical connection box compact for a high density arrangement.
In view of the above problems, it is an object of the invention to provide an electrical connection box having an improved space efficiency and a reduced number of mounting steps.